he never mentioned such creatures in the bible-----I can't help but question their existence for this very reason----I believe scientists discovered some form of prehistoric lizard----but nothing along the lines of gigantic walking amphibians-----what purpose would they have served---??

Wait, so dinosaurs were...amphibians? And because the bible doesn't say it (although your ilk are apt to believe that not only were dinosaurs real, they were mentioned in the bible, and walked with humans), it means it can't be real? But, the bible doesn't mention you, so you don't exist? It doesn't mention millions of things, that are all real. You fail, hard.